276 MINNESOTA BOTANICAL STUDIES 



not nearly as high as that in the alkahne lakes of other portions 

 of North America. Quoting from correspondence with Dr. E. E. 

 Free, of the above laboratory, it is seen that "the dissolved salts 

 present are mostly carbonates. The proportion of potassium salts 

 seems to be somewhat higher than normal but the waters are so 

 dilute that the samples at hand are hardly large enough for an accu- 

 rate determination of this element." A later letter from the same 

 laboratory reported that calcium was not found in any of the 

 samples; that potassium was present in all of the samples except 

 number 5 ; and that numbers 2, 4, 6, and 8 show both sodium and 

 potassium. 



The most noticeable possible correlation between the dissolved 

 solids and the vegetation of these lakes is that in the case of 

 numbers 1, 3, 5, and 7 the submerged and floating aquatics are very 

 greatly reduced. Species of Potamogeton, Myriophyllum, and 

 Nymphaea are relatively infrequent in such lakes. There is a very 

 pronounced difference in the abundance of all of the common 

 aquatics in numbers 4 and 8. Number 4 showed fewer species 

 and a much less abundance of submerged aquatics as compared with 

 number 8, and yet the total dissolved solids in the two lakes differed 

 by only 0.02 per cent. It may be, however, that the water of W'hite- 

 water Lake contains certain detrimental elements or ions that are 

 lacking in Hackberry Lake. Nothing definite can be concluded 

 in regard to this matter until we have made very extensive and 

 complete quantitative and qualitative analyses of these waters, and 

 have further supplemented these studies by data obtained from 

 carefully performed cultural experiments. Even then, since the 

 level of the lakes varies from season to season, and probably also 

 the concentration and composition of the waters, it may be im- 

 possible to point out a clearly defined correlation in all cases. 



The concentration of the waters of some of the lakes toward 

 the western portion of the hills is higher than that noted in any 

 of the above lakes. For instance Modesitt has published a brief 

 note (48) which indicates that some of the lakes contain high 

 percentages of dissolved salts. He found from analyses made by 

 the same laboratory as noted above that the total salt content runs 

 as high as 3.0 per cent in some cases, and that in one case 30.09 

 per cent of the total salt content was KjO. Where the waters are 

 so concentrated it is common to find, during dry seasons especially, 

 a pronounced crust of crystalline material upon the beach of these 



